New submissions for Tue, 20 Mar 18

Independent of Maxwell, in 1867 the Danish physicist L. V. Lorenz proposed a
theory in which he identified light with electrical oscillations propagating in
a very poor conductor. Lorenz's electrodynamic theory of light, which formally
was equivalent to Maxwell's theory but physically quite different from it, was
published in well-known journals in German and English but soon fell into
oblivion. In 1867 Lorenz also published a paper on his new theory in a
semi-popular Danish journal which has generally been overlooked. This other
paper is here translated into English and provided with the necessary
annotations.

In this paper we have two aims: first, to draw attention to the close
connexion between interpretation and scientific understanding; second, to give
a detailed account of how theories without a spacetime can be interpreted, and
so of how they can be understood.
In order to do so, we of course need an account of what is meant by a theory
`without a spacetime': which we also provide in this paper.
We describe three tools, used by physicists, aimed at constructing
interpretations which are adequate for the goal of understanding. We analyse
examples from high-energy physics illustrating how physicists use these tools
to construct interpretations and thereby attain understanding. The examples
are: the 't Hooft approximation of gauge theories, random matrix models, causal
sets, loop quantum gravity, and group field theory.

Subjects:Quantum Physics (quant-ph); History and Philosophy of Physics (physics.hist-ph)

It is usual to identify initial conditions of classical dynamical systems
with mathematical real numbers. However, almost all real numbers contain an
infinite amount of information. Since a finite volume of space can't contain
more than a finite amount of information, I argue that the mathematical real
numbers are not physically real. Moreover, a better terminology for the
so-called real numbers is "random numbers", as their series of bits are truly
random. I propose an alternative classical mechanics that uses only
finite-information numbers. This alternative classical mechanics is
non-deterministic, despite the use of deterministic equations, in a way similar
to quantum theory. Interestingly, both alternative classical mechanics and
quantum theories can be supplemented by additional variables in such a way that
the supplemented theory is deterministic. Most physicists straightforwardly
supplement classical theory with real numbers to which they attribute physical
existence, while most physicists reject Bohmian mechanics as supplemented
quantum theory, arguing that Bohmian positions have no physical reality. I
argue that it is more economical and natural to accept non-determinism with
potentialities as a real mode of existence, both for classical and quantum
physics.